Wearable consumer devices such as smart watches, activity monitors and health monitors have become popular in the past few years due to the rapid advancement in low cost semiconductor technologies. Such wearable consumer devices are integrating more and more features while form factors stay same or are further reduced. Accordingly, new types of interfaces and new ways to interact with wearable consumer devices are needed.
In some wearable consumer devices an RF radar system is employed to function as an interface. In some radar systems, the distance between the radar and a target is determined by transmitting a frequency modulated signal, receiving a reflection of the frequency modulated signal, and determining a distance based on a time delay and/or frequency difference between the transmission and reception of the frequency modulated signal. Accordingly, some radar systems include a transmit antenna to transmit the RF signal, a receive antenna to receive the RF, as well as the associated RF circuitry used to generate the transmitted signal and to receive the RF signal. In some cases, multiple antennas may be used to implement directional beams using phased array techniques.